The present invention relates to a one-way clutch to be employed in a starting system for an automobile or a motorcycle.
As shown in FIG. 6, an engine for an automobile or the like is started by the driving force of a starting motor (not shown) being transmitted to a crankshaft 131, which is a power transmission shaft. A one-way clutch 101 is arranged to prevent the generation of reverse-direction power after the engine has been started.
The one-way clutch 101 includes: an inner race 115 supported for rotation on the crankshaft 131 by a seizure-preventing member (for example, a roller bearing) 123; an outer race 102 concentric with and surrounding the inner race 115; and rollers 109 interposed between the inner race 115 and the outer race 102. The rollers 109 serve as torque transmitting members.
As shown in FIG. 7, the rollers 109 are placed in wedge-shaped first pockets 103 formed in the inner circumferential side of the outer race 102. A second pocket 104 is formed so as to be connected to the deeper end of the first pocket 103. A spring 113 is placed in the second pocket 104 to push the roller 109 toward the shallower end of the first pocket 103. The inner race 115 and the outer race 102 rotate together when the one-way clutch 101 is locked by the frictional engagement of the bottom (outer) surfaces 103a of the first pockets 103 and the outer circumferential surface of the inner race 115.
As shown in FIG. 6, a driven gear 121 is fixedly attached to the inner race 115 of the conventional one-way clutch 101. A boss member 111 and a rotor 124 fastened together with rivets 140 are fastened to a side surface of the outer race 102 by means of bolts 117.
The boss member 111 has an outer flange 110 extending annularly and perpendicularly to its axis, and a boss portion 106 axially extending from the inner circumferential edge of the outer flange 110. The boss portion 106 is fixedly mounted on the crankshaft 131.
The rotor 124 has an inner flange 127 extending annularly and perpendicularly to its axis, and a cylindrical wheel 125 axially extending from the outer circumferential edge of the inner flange 127. Magnets 130 are attached to the inner circumferential surface of the cylindrical wheel 125, to form a part of a generator.
The conventional one-way clutch 101 transmits the driving force of the starting motor (not shown) to the crankshaft 131 via the driven gear 121 and the boss member 111. In some cases, respective axes of the one-way clutch 101 (the outer race 102) and the boss member 111 may not be aligned, due to dimensional errors of holes for the bolts 117 or the like, because the boss member 111 is fastened to the outer race 102 of the one-way clutch 101 by means of the bolts 117. In such a case, the one-way clutch 101 and the boss member 111 cannot be closely connected to the crankshaft 131, and gaps may be formed between them. Thus, sometimes, rattling movement and/or rattling noise may be generated.
If the respective axes of the one-way clutch 101, the boss member 111 and the crankshaft 131 are not aligned, the transmission of the driving force tends to be biased (unbalanced) and thus the driving force cannot be satisfactorily transmitted. In such a case, a load acts on the crankshaft 131 in a direction perpendicular to the axis of the crankshaft 131, which may cause some troubles, such as the breakdown of the one-way clutch 101, in the engine.
In addition, the holes, into which the bolts 117 are screwed or inserted, have to be formed in the outer race 102 of the one-way clutch 101 and the boss member 111, which increases machining processes, reduces productivity and increases cost.
Accordingly, it is an object of the present invention to solve the foregoing problems, and to provide an inexpensive one-way clutch that does not rattle, does not generate noise, is capable of satisfactorily transmitting driving force, rarely develops trouble or breakdown, and can be efficiently produced.
This invention is a one-way clutch including: an inner race supported for rotation on a power transmission shaft; an outer race concentrically surrounding the inner race; and torque transmitting members interposed between the inner race and the outer race and capable of transmitting torque in one direction of the inner race to the outer race; wherein the outer race is integrally provided with an extending portion that extends inwardly in a radius direction thereof, and the extending portion is capable of being engaged with the power transmission shaft.
According to the feature, the respective axes of the extending portion and the inner race can be easily aligned with the axis of the power transmission shaft, such as a crankshaft. Consequently, the one-way clutch does not rattle, does not generate noise, is capable of satisfactorily transmitting driving force, rarely develops trouble or breakdown, and can be produced at a high efficiency at a low cost.
Concretely, the outer race and the extending portion are formed in a single member by, for example, forging.
Preferably, the outer race including the extending portion is subjected to a carburizing process to achieve desired high hardness. Then, the extending portion is subjected to a tempering process, to enable the extending portion to be machined so as to be fastened to the power transmission shaft. Alternatively, the outer race including the extending portion may be subjected to a carburizing process after the extending portion has been treated by an anticarburization treatment.
Alternatively, the carburized extending portion may be subjected to a carburized-part removing process after the outer race including the extending portion has been processed by a carburizing process. Alternatively, the outer race excluding the extending portion may be subjected to induction hardening after the outer race including the extending portion has been tempered.
Preferably, an axially extending cylindrical wheel (wall) is formed integrally with the outer race. In the case, the outer race, the extending portion and the cylindrical wheel may be integrally formed by, for example, forging.